The invention relates to a motorbrake for a Diesel engine with intake and exhaust valves and a high pressure fuel pump delivering fuel under pressure to a high pressure fuel supply line and a control line leading to an engine decompression valve for operating the decompression valve at the end of the engine compression stroke under the control of an electronic control device.
Motorbrake systems for commercial vehicle internal combustion engines which include a motorbrake valve in the engine exhaust pipe are well known. It is also well known that motorbraking performance can be further enhanced by fixed throttling structures serving as decompression valves which are continuously open during the motorbraking phase.
DE 39 04 497 C1 discloses a decompression brake comprising a hydraulic operating mechanism with a hydraulic cylinder and a hydraulic piston for controlling an exhaust valve of the internal combustion engine. The hydraulic operating mechanism and consequently, the exhaust valve, are actuated by the motor-driven injection pump by providing in the injection line leading to the injector a flow control device which interrupts the fuel supply from the injection pump to the injector and provides for communication with the hydraulic valve operating mechanism at the end of the compression stroke. The hydraulic valve operating mechanism then opens the exhaust valve slightly, whereby the air compressed during the compression stroke is discharged so that the energy transferred to the gas during the comprerssion stroke can not be returned to the engine during the following expansion stroke.
It is the object of the present invention to provide a motorbrake for a Diesel engine by which the braking performance can be adapted to the braking requirements and can be freely selected over the full engine rpm range.